Effect of nitrogen levels on grain yield and yield components of wheat (Triticum aestivum, L.) under irrigation and rainfed conditions

Document Type : Research Article

Abstract

Most areas under cultivation in Iran are located in arid and semiarid zones where water resources are limiting. This affects the grain yield and yield components of cereals. Nitrogen, as a key element in crop nutrition, has an important role in increasing crop yield and quality. It also enhances crop potential against environmental stresses such as drought. In order to study the effect of grain yield alleviation by nitrogen under drought stress conditions, a filed experiment was designed and conducted during 2004-2005 growing season at experimental farm of College of Agriculture Shiraz University. This research carried out in two individual parts (irrigated and rainfed) with factorial experiments and based on randomized complete block design with three replications. Treatments involved four levels of nitrogen (0, 50,100 and 150 kg/h) and five bread wheat cultivars "21" and Ghods genotype as "resistant" cultivars, Rahim with "medium resistance" and Bezostaya and Equa, as "sensitive" cultivars. The results showed that under water stress conditions, nitrogen enhanced, leaf area index and leaf area duration significantly. Increased leaf area and leaf area duration due to high levels of nitrogen, compared to control, resulted in significant increase in grain yield. Total dry matter was
decreased by drought stress under rainfed conditions. In both moisture regimes, with increased
nitrogen rate, dry matter production was increased and the negative effects of stress was alleviated. Ghods and 21 genotypes which appeared to have resistance to drought stress, with good yield components attained maximum grain yield and Equa had the minimum grain yield. Small difference between grain nitrogen content of genotypes was observed. Drought stress did not appear to affect nitrogen absorption under water stress conditions, although the mean grain nitrogen content was slightly lower under water stress conditions. Further research is recommended on sensitivity of Equa cultivar to drought stress and the possibility of using N fertilizer as a mean for alleviation of the adverse effects of drought stress on bread wheat yield.

20.1001.1.20081472.1388.7.1.31.9

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